Which factors of 36 are perfect squares?

The factors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, and 36. To determine which factors are perfect squares, we need to find the square root of each factor. The factors that have whole number square roots are perfect squares. In this case, the perfect squares among the factors of 36 are 1, 4, 9, and 36.